RF power detectors circuits (also referred to as RF power detectors) are widely used in various applications involving RF signals. For example, in a RF transmitter, RF power detectors may be used to monitor the power of the RF output signal. Measurement from RF power detectors may be used in a feedback control loop to generate RF output signal at predetermined power levels. In an antenna array, measurements from RF power detectors at all of the antenna elements may be used to detect antenna mismatch, as another example. In addition, RF power detectors may also be used as part of a calibration circuit for calibration, or in production testing circuit to determine whether a device is defective.
Challenges abound in RF power detector circuit design. For example, when RF power detector is inserted or coupled to a certain location of a RF circuit to measure the power of the RF signal, impedance mismatch may cause signal reflections that reduces the transmission efficiency and cause distortions to the signals to be measured. Additionally, output of RF power detectors may be affected by various factors such as the temperature, thereby degrading the accuracy of the measurements. There is a need in the art for RF power detectors that offers good performance (e.g., sensitivity, impedance matching, and robustness against temperature) over a wide RF frequency band.